Piazza Dei Miracoli

About Pisa & Tuscany

Construction of the Leaning Tower of Pisa

Begun in 1173, the process by which the leaning tower of Pisa had transformed into the monument as we know it today was long and drawn out. In fact, it took over 800 years from start to finish.

Intricate carvings, columns, arch's, and other design elements are incorporated into the construction of the tower. For medieval Europe, these types of design themes and construction processes were way ahead of their time, resulting in a structure that has remained timeless in appearance through the ages.

The tower was built with limestone and lime mortar, though the exterior of the tower is covered in marble. Ironically, the limestone is probably why the tower has not cracked and broken- the rock is flexible enough that it can withstand the pressures placed on it by the lean. It is doubtful that the original architect, Bonanno Pisano, had any idea that the qualities of limestone would play a role in preventing its ultimate collapse.

Originally, the leaning tower of Pisa was to be a bell tower for a cathedral. Five years after the initial construction of two floors it began to lean once the third floor was completed. At the time the cause of the lean was not known, though it was discovered many years later that the lean was the result of the tower being built on a dense clay mixture that was unable to fully support the weight of the tower.

As you can imagine, the construction process was halted for nearly 100 years. The architects of the time hoped that the soul would settle and harden over time, allowing them to resume construction and correct the lean.

100 long years passed before Giovanni di Simone constructed four additional floors. He had also intended to counteract the lean during the construction process but, like the original architects, made a critical miscalculation. The result was the four floors being built crooked, causing the tower to shift even more.

In 1372 the bell chamber was finally attached to the leaning tower of Pisa, and there were no further modifications or additions made until the 19 th century.

Alessandro Della Gherardesca decided to increase the value of the tower to the tourism industry by digging a pathway around the base of the tower that would allow tourists to see the detail that was put into the base. This took place in 1838, and resulted in the tower leaning even more when Gherardesca's workers struck water, flooding the ditches and increasing the tilt.

Benito Mussolini was the next to try his hand stabilizing the tower in 1934. He felt that the tower was an embarrassment to Italy and that it must be corrected and returned to a perpendicular state. As a result of his orders, 361 holes were drilled into the foundation of the tower and 90 tonnes of cement were used to fill them. The cement, rather than form up in the holes and act as a counterweight, sank into the clay beneath the structure, causing the tower to lean over even more.

End of Construction

The Leaning Tower of Pisa was closed for construction in 1990 and was then reopened once it was safe for everyone to tour. From start to finish, the leaning tower of Pisa took over 800 years to be constructed- probably the longest construction time in the world!